Tube structure



R. H. HOBROCK TUBE STRUCTURE Dec. 10, 1940.

Filed Nov. 29, 1939' Patented Dec. 10, 1940 UNITED STATES TUBE sTRUoTUnERaymond B. Hobrock, Grosse Pointe, Mich assignor to Bundy TubingCompany, Detroit, Mich a corporation of Michigan Application November29,1939, Serial No. 306,759

, Claims.

This invention relates to tube structure, and it has to do with tubingmade from strip metal stock.

The principal object of the invention is the.

5 provision of a novel tube Structure comprised of at least two metalstrips, one of which has corrosion resisting characteristics, while theother is for imparting strength and body to the tube, and need not havecorrosion resisting characteristics.

The corrosion resisting metalis usually relatively expensive, and inorder to produce the tube cheaply this strip is preferablyrelativelythin. The structure is such that a strip of corrosion re.

. sisting metal, which may be relatively thin, forms the outer andinnersurfaces of the tube, while the strength impartingstrip isconflnedwithin the tube wall, and it gives to the tube wall, requisitethickness, body and strength, The strength giving strip may berelatively thick, but this is subject to variation, depending uponrequire- 7 ments as to strength, tube wall thickness, etc.

In carrying out the invention a number of corrosion resisting metals maybe used for the one strip, such, for example, as nickel, copper, Monelmetal, and in some instances, silver or gold, or various alloys of theabove or similar metals, while the strip for giving body and strength tothe tube may be a ferrous metal such as a low carbon steel. There may beinstances, however,

where a non-ferrous metal would be desirable as the strength givingstrip, used probably in conjunction with a corrosion resistant strip ofmore expensive metal.

A tube structure for carrying out the invention stock. The other stripof stock has a considerably greater width, considered in the flat form,and it is fashioned so as to substantially completely envelop theferrous metal strip. This is the corrosion resistant metal and isfashioned to r form an outer ply 2 and an inner ply 3. An intermediateportion of this strip is fashioned to extend from the outer ply to theinner ply and so as to lie between the adjacent edges of the strengthgiving strip. This intermediate portion is shown at l. The-corrosionresisting metal is thus fashioned through, substantially 360 to form theouter ply 2, and is formed with the oilset portion 4, and -'fashionedsubstantially through 360 to form the inner ply. J p

The edges of the strength giving strip are pref- 5 erably fashioned withcontours of a substantially mating nature and which facilitate the formation of the offset 4. For example, one edge of the strip i is preferablyrounded or formed on a radius as at! and provided with a relativelysharp-Q 10 ly extending; edge 6, while the other edge in a matingfashion is similarly formed on a'radius 'l with an extending edge 8. Theofiset 4 thus is not fashioned or bent too abruptly from the inher andouter plies, but joins thereto on generous l5 curves.

The edges of the strip l accordingly slightly overlap each othercircumferentially, although spaced apart by the offset 4.

This tube may be fashioned from two strips of metal stock which aremoved lengthwise from 20 reels or rolls and fashionedinto tubular formby a suitable tube forming mill, the general arrangement of which is.well known to those versed in the art. The tube is sealed by unitingthe contiguous surfaces of the plies and joints. Both the 25 inner andouter pliesof the corrosion resisting metal are united'to the contiguoussurfaces of the strength giving ply and the ofiset 4 is united 7 to theedges of the strength giving ply. The I edges of the corrosion resistingmetal are brought 30 parts. .The curved portions 5 and I of the strip 1form a supporting base for the adjacent curved portions in the corrosionresisting strip so that 40 considerable pressure may be applied at theedges. The tube is preferably sealed by the use of a molten sealingmetal such as a 'soft solder, or a hard solder'or brazing metals, theselection of which may be influenced by the requirements of 45 thefinished tube and by the particular metals employed invthe tube. Softsolders are those which melt at a relatively low temperature, such as amixture of tin and lead, while hard solders or brazing metals meltat-higher temperatures, 50

and accordingly thus would form a .tube capable of withstanding highertemperatures in use. In some instances, as for example, where the-stripsforming. the tube are of steel and Monel inetal,' the sealing metal maybe substantially pure coppletely envelop the first strip.-

per, which, insofar as the present invention is concerned, may be calleda brazing metal. In some instances it may be feasible to fuse the metalof the strips without a third sealing metal. All these variations arecovered by the language used in the appended claims which, in effect,state that the surfaces are united by a fused sealing metal.

Thus a tube is formed, the novel structure of, which employs a singlestrip for the inner and outer plies which completely envelops, except,of course, for the ends, the intervening strength giving strip. Thecorrosion resisting metal may, of courseg'. be quite thin, but in thisregard it is to be pointed out that even though the corrosion resistingmetal is thin, it is to be distinguished from a tubing which merely hasa plating or coating of metal which may be formed, for example, byprocesses such as a hot dipping process or an electroplating process.The corrosion resisting strip is thus a structural part of the tube andnot merely a thin coating or plating. Tubing of this kind can be made invarious sizes and may be used for fluid conducting purposes or forstructural ,or semi-structural purposes, wherever corrosion resistingcharacteristics are desired,

I claim:

1. A tube comprising, a metal strip fashioned substantially into tubularform with its edges in spaced facing relationship, another metal striphaving a part fashioned around and contiguous to the outer surface ofthe first strip, a part ex tending between and contiguous to the edgesof the first strip and a part'fashioned into tubular form inside of andcontiguous to the inner surfaces of the first strip, edge portions ofthe second strip being disposed in contiguous relationship to some ofthe said aforementioned parts of the second strip, the contiguoussurfaces; of the strips and the contiguous surfaces of the edge portionsand said parts of the second strip being united by fused sealing metalto seal the tube and substantially completely envelop the first strip.

2. A tube comprising a metal strip fashioned into tubular form with itsedges in spaced facing relationship, said strip being relatively thickto -give the tube body and strength, another metal strip of relativelythin corrosion resisting metal having a part fashioned around andcontiguous to the outside surfaces of the first strip, a part extendingbetween and contiguous to the edges of the first strip and a partfashioned into tubular form inside the first strip and contiguous to theinner surfaces thereof, edge portions of the second strip beingcontiguous tosome of the aforementioned parts of the second strip, thecontiguous surfaces of the two strips and the contiguous surfaces of theedge portions and said parts of the second strip' being united by fusedsealing metal to seal the tube and substantially com- 3. A tubecomprising, a relatively thick ferrous metal strip fashioned intotubular form with its edges in spaced facing relationship, anotherstripof relatively thin corrosion resisting metal having a partfashioned into tubular form outside of and contiguous.to the outersurfaces of the first strip, a part fashioned into tubular form insidethe first strip and contiguous to the inner surface thereof and anintermediate integral part lying between and contiguous to the edges ofthe first strip and connecting the inner and outer tubular forms of thesecond strip, edge portions of the second strip being disposed incontiguous relationship to some of the aforementioned parts of thesecond strip, the contiguous surfaces of the two strips and thecontiguous surfaces of the edge portions and the said parts of thesecond strip being united by fused sealing metal to seal the tube andsubstantially'completely envelop the 4. A tube comprising, a relativelythick metal strip fashioned into tubular form and having its edgesdisposed in spaced facing relationship, the edges being of beveledformation so as to overlap each other circumferentially, another stripof relatively thin corrosion resisting metal having a part fashionedinto tubular form around and contiguous to the outer surfaces of thefirst strip, a part fashioned into tubular form inside of and contiguousto the inner surfaces of the first strip,

and an intermediate integral part lying between and contiguous to theedges of the first strip and connecting the inner and outer tubularforms of the second strip,'edge portions of the second strip beingdisposed-in contiguous relationship with some of the aforementionedparts of the second strip, the contiguous surfaces of the two strips,and the contiguous surfaces of the said edge portions and parts of thesecond strip being united by fused sealing metal to seal the tube andsubstantially completely envelop the first strip.

5. A tube comprising, a relatively thick metal strip fashioned intotubular form and having its edges disposed in spaced facingrelationship, the

edges being-of beveled formation so as to overlap each othercircumferentially, the contour of the strip substantially at thejuncture where the edges meet the surfaces of the strip at an obtuseangle presenting a curved formation, another strip of relatively thincorrosion resisting metal having a part fashioned into tubular formaround and contiguous to the outer surfaces of the first strip,

a part fashioned into tubular form inside of and contiguous to the innersurfaces of the first strip, and an intermediate integral part lyingbetween and contiguous to the edges of the first strip and connectingthe inner and outer tubular forms of the second strip, said intermediatepart joining with the inner and outer tubular formations on curved lineswhere the same passes over the curved formations of the first strip, theedges of the second strip being beveled and disposed contiguous to thesaid curved portions of the second strip, the contiguous surfaces of thetwo'strips and the contiguous surfaces of the edge portions and curvedportions of the second strip being united by fused sealing metal to sealthe tube and substantially completely envelop the first strip.

RAYMOND H. HOBROCK.

